Using a balanced, randomized, crossover design, single intravenous (1 mg/kg) or oral (3 X 100 mg) doses of acebutolol were administered at weekly intervals to 6 healthy volunteers. For each subject venous blood samples and timed urine collections were obtained after each treatment. Plasma and urinary acebutolol levels were measured by a spectrophotometric method that measures acebutolol and its N-acetyl metabolite (which has equivalent cardiac activity). Using a computer program, various pharmacokinetic parameters were estimated from the data of each subject. From the intravenous data (obtained up to 6 hr after dosing), the following mean (±SD) values were found: distribution half-life (T½D), 0.60 (±0.43) hr, plasma elimination half-life (T½El), 3.2 (±1.1) hr, apparent volume of distribution (VD), 224 (±69) L, and apparent VD/kg, 3.0 (±0.8) L/kg. Using the oral data (obtained up to 10 hr after dosing), the value for T½El was 3.2 (±0.9) hr. The mean cumulative urinary recovery (expressed as % dose) after the intravenous route was about 60%, while that after the oral route was of the order of 35%, suggesting that about half of the oral dose reached the systemic circulation. The mean creatinine clearance of the 6 subjects was 103 (±7) ml/min, while the value (obtained between 2 and 4 hr after intravenous dosing) for renal clearance of acebutolol as measured was 298 (±68) ml/min and the corresponding plasma clearance was 818 (±64) ml/min. These results support the occurrence of substantial nonrenal elimination and renal tubular secretion.